Among the wardrobes, bookshelves and the like available in recent years there are included assembly type ones which are provided in a so-called knockdown fashion for being assembled by the user. In such an assembly type bookshelf or the like, screws as so-called connectors are used for connecting shelf boards disposed in the lateral direction to frame boards disposed in the vertical direction.
More particularly, as shown in FIG. 22, screws 2 are threaded into a cross board 3, used as a shelf board, from the outsides of frame boards 1 which form vertical surfaces the screws are inserted through holes 1a formed beforehand in the frame boards 1 and then through end faces of the cross board.
However, such method of connecting the cross board 3 to the frame boards 1 by using the screws 2 can be applied to the case where two frame boards 1 are present right and left and cannot be applied to the case where three or more frame boards 1 are arranged in parallel.
In other words, as to relatively large-sized bookshelves and the like including three or more frame boards 1 arranged in parallel, it is impossible to provide them in a knockdown fashion.
On the other hand, in houses of recent years, bookshelves and the like are often provided as built-in structures in which they are buried in walls. But in case of post-mounting of such built-in type bookshelves or the like and in case of connecting the cross board 3 to the frame boards 1 which form vertical surfaces, there is adopted a so-called nailing method which uses nails 4 as connectors for connecting the cross board 3 to the frame boards 1.
Such nailing method is applicable also to the case where three or more frame boards 1 are arranged in parallel and cross boards 3 are disposed between. adjacent frame boards.
In this case, however, since the nails 4 are driven in obliquely from the lower surface side of each cross board 3. Disadvantages are caused such that the nailing work is not easy and it is difficult to ensure against disengagement of the cross board 3 from the frame boards, namely durability.
In view of the above point, in the case of using the nails 4, a metallic support piece 5 can be disposed between the underside of each cross board 3 and the inside face of each frame board 1, as indicated with phantom lines in FIG. 23. Also a groove 1b can be formed in the inside face of each frame board 1, and an end portion of the cross board 3 is inserted into the groove 1b, as indicated also with phantom lines in the same figure.
However, in the above method using the metallic support pieces 5 or the grooves 1b, an increase in the number of working steps results. In recent years, the cost required for the execution of this type of operations has been increasing, and the large cost for obtaining a desired bookshelf or the like is inconvenient.
Besides, the nailing method referred to above is not applicable to the foregoing knockdown system and therefore a large-sized bookshelf or the like cannot be provided according to the knockdown system.
For example, in providing a stair handrail structure by a post-mounting method and for connecting an end portion of a bar member which forms the handrail to a vertical surface such as a wall or the like, as shown in FIG. 24, there has heretofore been no other method than the nailing method. In this method an end face of the handrail 7 is held as a bar member held in an abutted state against a wall 6 which forms a vertical surface. Nails 4 are driven in from the lower surface side of the handrail in the same manner as mentioned previously.
Also in this case, with nailing alone, the durability is not very reliable. Therefore it is necessary to separately use auxiliary metal fittings (not shown), so that a large cost is required for obtaining a desired stair handrail structure as in the foregoing case.